The major Matlab clones are Scilab, Octave, and Rlab. None are true "clones", because none offer 100% compatibility with Matlab's "m-files". However, they all provide number-crunching power similar to Matlab, at a much better cost/performance ratio (since they're free!)
Essentially, Scilab, Octave, and Rlab are interpreted, matrix-based programming languages. They share with Matlab:
In some ways, Scilab may be the "best" of the Matlab clones. Scilab has many strengths, including excellent documentation (the signal processing manual is an education in itself!) and excellent support (via e-mail and its own newsgroup). Best of all, for Windows users, Scilab is supplied not only as source code, but as a Windows binary. Scilab is mostly--but not completely--compatible with Matlab. (Scilab now comes with a Matlab-to-Scilab translator, but that's still a bit immature.) For more information:
Like Scilab, Octave is another mature, high-quality Matlab clone. If you use a Unix-like operating system, Octave may be a better choice than Scilab because it reportedly offers better compatibility with Matlab. (However, for Windows users, Octave suffers the comparitive disadvantage that the binary distribution of it is quite complicated to install.) For more information:
Rlab is the least Matlab-compatible of the three. Rlab does not try to be a Matlab clone but instead, in the words of its creator "borrows what I believe are the best features of the Matlab language and provides improved language syntax and semantics." For more information: